1. Field of the Invention
The present invention relates to lamp starting and operating procedures in electronic ballasts for fluorescent lamps, particularly with respect to providing gentle yet affirmative lamp starting as well as effective protection against electric shock hazard.
2. Description of Prior Art
In conventional electronic ballasts for so-called Rapid-Start fluorescent lamps, the procedure for starting the lamps provides for simultaneous application of cathode heating power and a lamp ignition voltage of magnitude high enough to cause the lamps to ignite as soon as the cathodes have become thermionic. With the many different types of fluorescent lamps presently available, the magnitude of the lamp ignition voltage for igniting the most-difficult-to-ignite lamps is so high as to result in premature ignition of the least-difficult-to-ignite lamps. As a result, the least-difficult-to-ignite lamps are subjected to a pre-ignition glow current of unacceptably large magnitude, thereby giving rise to substantial shortening of their life expectancies.